This one will also do it, and allow for a little upgrade room should you decide on higher end cards. Mine has been stellar so far(3 months), and it just happens to be a great deal right now with the rebate which I had no trouble getting. http://www.newegg.com/Product/Product.aspx?Item=N82E168...
450 Watt or greater power supply with one 75W 6-pin PCI Express® power connectors recommended (600 Watt and two 6-pin connectors for ATI CrossFireX™ technology in dual mode)
^ This is straight from the AMD site.
I would NOT use a 500w PSU with 600w being recommended. That would be a generic 600 watt unit but I would not risk a 500w unit as was recommended above. Also that OCZ linked to is a decent power supply but you can do better for the same money.
A good 500 watt PSU will do nicely. A pair of 5750's will pull about 150 watts (12 - 13 amps) at load.
One of my systems has an OC'd Q9550, 4 GB RAM, a GTX260 - a card with similar power requirements to two 5750's, a Gigabyte EP45-UD3P motherboard, 3 hard drives (2.6 TB total)and an optical, and a Soundblaster card all powered by a Corsair 750TX.
Running 3 instances of Prime95 to load the CPU and 3DMark06 to load the GPU, it pulls 375 watts from the wall as measured by my Kill-a-Watt meter. Figuring 80% PSU efficiency, the system pulls 300 watts from the PSU.
Scroll down the page to the power consumption section. These guys are using a 130W cpu and they have it overclocked so it is drawing more than that. With crossfire 5750's they measured a peak of 425W. Though they do recommend a 600W power supply(the same as AMD). Things will probably work just fine with a quality 500W so if you have one already then stick with it. If not, then just get what AMD recommends.